This paper aims at testing the mechanical relevance of the petrological model of anorthosite massif diapiric emplacement. The Egersund-Ogna massif (S. Norway) is of particular interest because recent ... [more ▼]

This paper aims at testing the mechanical relevance of the petrological model of anorthosite massif diapiric emplacement. The Egersund-Ogna massif (S. Norway) is of particular interest because recent petrological and geochronological data constrain the initial geometry, emplacement conditions and timing (about 2 m.y.). The formation of this anorthosite massif is in agreement with the classical petrological model, in which accumulation of plagioclase takes place in a deep-seated magma chamber at the crust-mantle limit, from which masses of plagioclase separate and rise through the lower crust up to the final level of emplacement at mid-crustal depths. The Egersund-Ogna massif also displays a foliated inner margin, in which strain ellipsoids have been reconstructed by investigating at 51 sites the deformation of megacrysts of high-alumina orthopyroxene. Based on these petrological data, a model made up of one rigid layer (upper granitic crust) and three viscous layers (lower part of the granitic crust, noritic lower crust and anorthosite) has been built up. The upper crust behaviour is represented by an elastoplastic law and the viscous layers obey elastic-viscoplastic laws with Newtonian viscosity. An inverse density gradient is considered between the lower crust (d = 3.00) and the anorthosite (d = 2.75), the loading consisting only in gravity. The modelling is carried out under axisymmetrical conditions, using the LAGAMINE finite-element code coupled with an automatic re-meshing algorithm designed to deal with large strains in complex structures. The results show that, from a mechanical point of view, the diapirism model is a robust and consistent assumption for the emplacement of anorthosites, because realistic diapir and rim-syncline shapes are obtained. Moreover, the numerically obtained emplacement time (about 2.5 m.y.) is in agreement with the available geochronological data, and the computed strain field is coherent with field measurements, especially regarding the circumferential extension, which becomes the largest extension strain component in the expansion phase. (C) 1999 Elsevier Science B.V. All rights reserved. [less ▲]

The Gulf of Corinth in Greece is an active continental rift propagating westward toward the Aegean subduction zone. GPS data shows that deformation rate reaches a maximum of 15 mm/yr at its western tip ... [more ▼]

The Gulf of Corinth in Greece is an active continental rift propagating westward toward the Aegean subduction zone. GPS data shows that deformation rate reaches a maximum of 15 mm/yr at its western tip. The style of extension and strain distribution is well documented offshore in the eastern and central parts of the rift (Bell, 2009). At its most active western extremity, published offshore data is not sufficient to characterize the deformation pattern. High resolution seismic profiles were thus acquired in that region within the framework of the SISCOR project to improve our understanding of fault evolution, seismicity and to be able to construct mechanical models of deformation. Here we investigate the spatio-temporal pattern of the basin subsidence and deposition with sparker data acquired in November 2011. Active faults and correlative time horizons were first mapped. The stratigraphy was then correlated with the eustatic sea-level curve. This sequence stratigraphic interpretation is possible because there are strong glacial-interglacial variations in the depositional environment. In fact lacustrine conditions prevail within the gulf during glacio-eustatic lowstands and are characterized by low amplitudes seismic facies. So synrift sediment isopachs over the last 12 000 and 130 000 yrs could be produced. The interpreted data allow us to: (1) compare deformation pattern at the western tip of the Gulf with the more mature central and eastern part of the Rift; (2) constrain the pattern and the timing of deformation as well as rates of faulting. Reference Bell, R. E., McNeill, L. C., Bull, J. M., Henstock, T. J., Collier, R. E. L., & Leeder, M. R., 2009. Fault architecture, basin structure and evolution of the Gulf of Corinth Rift, central Greece. Basin Research, 21(6), 824-855. doi:10.1111/j.1365-2117.2009.00401.x [less ▲]

The assessment of wall structures featuring low aspect ratios remains a challenging problem due to their complex deformation patterns and susceptibility to sudden shear failures under seismic actions. To ... [more ▼]

The assessment of wall structures featuring low aspect ratios remains a challenging problem due to their complex deformation patterns and susceptibility to sudden shear failures under seismic actions. To address this issue, a three-parameter kinematic theory (3PKT) for shear-dominated walls has been recently proposed by Mihaylov et al. (2016). This rational approach uses only three degrees of freedom to predict the complete load-displacement response of a member, and captures shear failures occurring prior to or after the yielding of longitudinal reinforcement. Due to its relative simplicity and computational effectiveness, the 3PKT can be used for the performance-based evaluation of existing structures. To further validate and extend the kinematic approach, an experimental program was performed at the University of Liege, and is the focus of this paper. The test campaign consisted of testing to failure of three cantilever walls with an aspect ratio of 1.7, which featured uniformly distributed longitudinal and transverse reinforcement. The main test variable was the level of axial load which has a significant impact on the failure mechanism and lateral displacement capacity. In addition to more conventional measurements using displacement transducers, the experiments involved the measuring of the complete deformation patterns of the walls using an optical LED system. This paper presents the main test results in terms of load-displacement responses, crack patterns and failure modes. The walls developed major diagonal cracks but failed in flexure-dominated modes. The measured deformation patterns are compared to the patterns predicted by the kinematic model for shear-dominated walls. Even though the failure of the test specimens was governed by flexure, their deformations were predicted well by the model. [less ▲]

This paper presents a three-parameter kinematic model for the deformation patterns of deep continuous transfer girders. The three degrees of freedom of the model are the average strains along the top and ... [more ▼]

This paper presents a three-parameter kinematic model for the deformation patterns of deep continuous transfer girders. The three degrees of freedom of the model are the average strains along the top and bottom longitudinal reinforcements within each shear span, as well as the transverse displacement in the critical loading zone. The model is validated with the help of a large test of a two-span continuous beam performed at the University of Toronto. It is shown that the apparently complex deformation patterns of the specimen are captured well by the kinematic model. [less ▲]

This article describes the deformation of an elastic pipe submitted to gravity and to an internal fluid flow. The pipe is clamped horizontally at one end and free at the other end. As the fluid velocity ... [more ▼]

This article describes the deformation of an elastic pipe submitted to gravity and to an internal fluid flow. The pipe is clamped horizontally at one end and free at the other end. As the fluid velocity increases, the shape changes from an elastic beam deflected by its own weight towards an horizontal posi- tion. The shape of the pipe is characterized experimentally and is compared with a theoretical model based on the Euler-Bernoulli approximation and the conservation of the fluid momentum. We study how the determination of the pipe deformation provides an estimation of the conveyed fluid flow. Finally, the vertical force produced by the conveyed fluid to lift off a mass is deduced. [less ▲]

The study of the deformations undergone by a soap bubble submitted to an electrical force began with Taylor and Wilson 1 and the observation of the so-called Taylor’s cones. Beyond this particular ... [more ▼]

The study of the deformations undergone by a soap bubble submitted to an electrical force began with Taylor and Wilson 1 and the observation of the so-called Taylor’s cones. Beyond this particular structure, few studies analyzed the bubble deformations. For example, what is the link between the deformations and the electrical force ? Or, how do charges move in the thin soap film formed by the bubble ? To answer those questions, we characterize the shape variations of the surface of the bubble immersed in the uniform electric field of a plan capacitor. In particular, our study focuses on hemispherical bubbles lying on the bottom electrode of a plane capacitor. This study allows us to observe some interesting phenomena like the appearance of a hysteresis cycle in the deformation amplitude. [less ▲]

This work presents some important features of the normal articular structures and a definition of the degenerative osteo-arthropathy that points the involvement of all the joint structures. The pathogeny ... [more ▼]

This work presents some important features of the normal articular structures and a definition of the degenerative osteo-arthropathy that points the involvement of all the joint structures. The pathogeny of the pathology is tackled by the potential risk factors and by the cartilage-cartilage, synovium-cartilage and bone-cartilage cycles that lay particular emphasis on the interaction between the different joint structures. The diagnostic tools of the degenerative osteo-arthropathy like the conventional or recent imaging techniques (magnetic resonance imaging, scintigraphy and tomography) and the biomarkers of the cartilage and bone metabolisms are listed. The pathogeny of the degenerative osteo-arthropathy is complex and involves different factors. This disease is characterised by an imbalance between the anabolic and catabolic processes of the cartilage metabolism. Inflammation is also present and lead to the clinical signs. The synovitis, the liberation of degradation mediators, the mechanical stresses and/or the subchondral bone are part of the pathogeny at different degrees. The development of recent imaging techniques and the biomarkers of the cartilage and bone metabolisms allow the precise description of the lesions and give some additional information on the pathogeny of the osteo-arthropathy. These recent techniques raise new questions and allow the in-depth analysis of the study of the osteo-arthropathy. [less ▲]